Preview

Solar panel recommended (Score: 2, Informative)

You can use it to charge your cell phone (with any 12V car charger), or to charge your FIOS/U-Verse/cable-modem battery (requires in-line diode). And even without a ($40!) battery, you can use the panel for power directly, but only during daylight hours. It's equally useful to charge flashlight and radio batteries...

You just have to be careful about duty cycle with solar. In winter, with just 8 hours of low-angle sunlight, possibly over-cast weather, you might only get a very small amount of power from it. So be sure to always significantly over-spec.